Authorization and its enforcement, access control, has stood at the beginning of the art and science of information security, and remains being a crucial pillar of secure operation of IT. Dozens of different models of access control have been proposed. Although enterprise architecture as a discipline strives to support the management of IT, support for modeling authorization in enterprises is lacking, both in terms of supporting the variety of individual models nowadays used, and in terms of providing a unified metamodel capable of flexibly expressing configurations of all or most of the models. This study summarizes a number of existing models of access control, proposes an unified metamodel mapped to ArchiMate, and illustrates its use on a selection of simple cases.